This invention relates to systems for automatic feeding of documents and, in particular, automatic feeders designed to operate with scanners for optically scanning printed forms and the like.
Scanning devices for scanning printed sheets and forms have taken on increased importance in many areas. For example, in the area of forms used for obtaining test information, or information of any sort which is recorded manually by a person who is filling out a form, it is very important to be able to automatically process the form to as great as extent as possible to derive the information therefrom. Thus, as used by the assignee of this invention, a Terminal Data Corporation 4140 paper transport scanner is utilized for scanning documents and forms, e.g. up to 11.times.17 inches. The scanner has a mechanism for transporting the document from the scanner bed, where it may be manually positioned, into the optical scanning area, performing the optical scanning and generation of corresponding digital data, and then ejecting the document out the other end. In this commercially available device, the transport mechanism positions the document somewhat crudely in the scan area, the exact position being very much a function of where the document is manually positioned on the scanner bed prior to its being transported into the scanner.
As can be appreciated, in applications where a great volume of documents is to be scanned, it is highly important, and indeed imperative, to provide automatic feeding into the scanner. Not only is automatic feeding required in order to increase through-put, but for reliable high-speed operation there must be provided an automatic feeder mechanism for automatically aligning the forms, or sheets, as they are fed to the scanner bed. What is desired, and has heretofore been unavailable, is an automatic feeding mechanism that not only is capable of operating at high speed, but which positions the documents to be scanned with a high degree of accuracy, so that when they are taken over by the scanner, they are in turn positioned for accurate optical imaging and scanning. Further, in order to achieve a high rate of through-put, it is required that the feed mechanism be controlled so as to provide the next sheet, or form, the very instant when the scanner is ready to be primed with a next form, and to avoid feeding a following sheet before the scanner is in position to accept it.